A technology disclosed in JP-A-2007-132203 effectively improves the responsiveness of torque generated by an internal combustion engine. When the amount of torque control for generating a target torque is to be calculated, the disclosed technology compensates the difference between an estimated torque, which is estimated from a target torque control amount, and a target torque for a control response lag. Next, the obtained difference, which is now compensated for the control response lag, is added to the target torque. A torque control amount is then calculated from the resulting target torque. This conventional technology makes it possible to calculate a control amount by accurately compensating it for a control response lag. Therefore, when various devices of the internal combustion engine are controlled in accordance with the calculated control amount, the responsiveness of torque generated by the internal combustion engine can be improved.
However, the above conventional technology has room for improvement in torque controllability. The conventional technology compensates for the response lag of the estimated torque relative to the target torque by increasing the torque control amount. However, the amount of such a torque control amount increase is determined in accordance with the result of adaptation to a real machine. Therefore, if the degree of adaptation is insufficient or the performance of the real machine greatly varies, a torque overshoot may occur due to an excessive increase in the torque control amount. If the responsiveness of torque is insufficient, the driver of a vehicle cannot achieve a desired vehicle behavior. Similarly, if torque controllability is insufficient, the driver cannot achieve a desired vehicle behavior either.